Remove generated NewXWithDefaults methods and related documentation

[averche]

Description

Removing New__WithDefaults generated methods since they are not particularly useful and somewhat confusing as explained in #194.

Also cleaning up some of the old generated documentation parts within the model docs.

Resolves #194

How has this been tested?

Relying on CI.

[dhuckins]

are there any files that are worth taking a look at? (1,115 is a lot!)

[averche]

The changes are only in the three generate/templates/*.handlebars files. The rest are generated but should give you an idea on what's changed :)